Misc trivial improvements around circpadding code.

doc/tor.1.txt

@@ -1025,6 +1025,11 @@ The following options are useful only for clients (that is, if
     to use for "middle" hops in your normal circuits.
     Normal circuits include all circuits except for direct connections
     to directory servers. Middle hops are all hops other than exit and entry. +
++
+    This is an **experimental** feature that is meant to be used by researchers
+    and developers to test new features in the Tor network safely. Using it
+    without care will strongly influence your anonymity. This feature might get
+    removed in the future.
 +
     The HSLayer2Node and HSLayer3Node options override this option for onion
     service circuits, if they are set. The vanguards addon will read this

src/core/or/circuitpadding.c

@@ -304,6 +304,7 @@ circpad_histogram_usec_to_bin(const circpad_machine_state_t *mi,
   else
     start_usec = state->start_usec;
 
+  /* The first bin (#0) has zero width and starts (and ends) at start_usec. */
   if (usec <= start_usec)
     return 0;
 

src/core/or/relay.c

@@ -527,6 +527,7 @@ relay_command_to_string(uint8_t command)
     case RELAY_COMMAND_EXTEND2: return "EXTEND2";
     case RELAY_COMMAND_EXTENDED2: return "EXTENDED2";
     case RELAY_COMMAND_PADDING_NEGOTIATE: return "PADDING_NEGOTIATE";
+    case RELAY_COMMAND_PADDING_NEGOTIATED: return "PADDING_NEGOTIATED";
     default:
       tor_snprintf(buf, sizeof(buf), "Unrecognized relay command %u",
                    (unsigned)command);